Question
Sat November 05, 2011 By: Pratibha Kamath

1)Why does the sound from the sun not reach us when light and heat energy do reach us? 2)how is it that sound travels in the form of transverse waves in plasma while it travels in the form of longitudinal waves in air ?

Expert Reply
Mon November 07, 2011
1) Electromagnetic energy from the sun comes to Earth in the form of radiation. Sound is not a form of electromagnetic energy. Because sound is really the energy of the motion of molecules through a medium (mechanical energy), it cannot travel through a vacuum. Electromagnetic energy has no need for a medium through which to travel, and can therefore travel through space from the sun to reach the Earth so only light and heat energy reach us
 
2) Sound waves propagate via air molecules bumping into their neighbors. This transfers some energy to these neighbors, which will cause a cascade of collisions between neighbouring molecules. When air molecules collide with their neighbors, they also bounce away from them (restoring force). This keeps the molecules from continuing to travel in the direction of the wave results into longitudinal waves in air.
plasma waves must be generated from an electrical or magnetic source. A laser is an example of a device which produces plasma waves when it interacts with ionizing gases. This type of longitudinal wave can exist in an ionized or charged state. An electromagnetic wave can also take the form of a transverse wave
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